In radio, longwaveor long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with relatively long wavelengths.
In contemporary usage, the term longwave is not defined precisely, and its meaning varies across the world. Most commonly, it refers to radio wavelengths longer than 1000 metres; frequencies less than 300 kilohertz.
In Europe, Africa and large parts of Asia (International Telecommunication Union Region where a range of frequencies between 148.5 and 283.5 kHz is used for AM broadcasting.